When I was at Air Wis there was no policy against it. That was 10 years ago.
At another regional I don’t remember the verbiage in the FOM, but two pilots had multiple forearm tattoos.
I understand your points, and think the route of least resistance is just covering up all tattoos for what you mentioned.
Bottom line to the OP, you’re fine. They’ll never see or know about them until after you’ve been hire (not counting them looking at all your social media photos).